Distinct glucose-lowering properties in good responders treated with sitagliptin and alogliptin

All dipeptidyl peptidase 4 (DPP-4) inhibitors display similar glycemic efficacies, although they differ greatly in their chemical structures and pharmacological properties. This may be due to the inclusions of non- or poor-responders in the analysis, thereby masking the real effects of these drugs. The aim of this study was to identify any differences in diabetic parameters only in good responders treated with sitagliptin and alogliptin.

Treatment naïve subjects with type 2 diabetes mellitus were assigned to either sitagliptin 25-50 mg/day (n = 69) or alogliptin 12.5-25 mg/day monotherapy (n = 62) for 3 months. Only those who showed good response selected by a novel parameter called A1c index were further analysed (n = 24 for sitagliptin and n = 21 for alogliptin).

At baseline, FBG and BMI were significantly higher and CPR-index was significantly lower in alogliptin good responders. At 3 months, while similar reductions of HbA1c were observed in these two groups, decreases of fasting blood glucose (FBG) were significantly higher in alogliptin good responders. Homeostasis model assessment (HOMA)-R significantly decreased only in alogliptin good responders, while HOMA-B similarly and significantly increased in these two groups. BMI significantly increased only in sitagliptin good responders. Significant negative correlations were observed between A1c index and changes (Δ) of HOMA-B in both groups. By contrast, significant positive and negative correlations were observed between ΔFBG and ΔHOMA-R, and between ΔFBG and ΔHOMA-B, respectively, only in alogliptin good responders.

These results implicate that the effects on diabetic parameters and the glucose-lowering mechanisms of these two drugs might be different in those who have good response with these drugs. Accordingly, the choice of these drugs may be dependent on the characteristics of the patients.